1. Technical Field
The present invention relates generally to safety devices and, more particularly, to fall arresting devices including retractable lifelines.
2. Background Information
Retractable lifeline safety devices generally include a housing containing a drum with a cable or rope wound onto it. The drum is spring biased to retract any of the cable that is unwound from it once tension on the cable is reduced. Also included within the housing is a brake system for stopping rotation of the drum if cable suddenly unwinds from it at a rate greater than a predetermined maximum angular velocity. The device may be mounted to a structure on which a worker is performing a task, such as a bridge or a building, with the end of the cable or rope being attached to the worker's belt or body harness. Alternatively, the device may be mounted directly to the worker's harness, with the other end of the cable being mounted to the structure on which the worker is working. Should the worker fall from the scaffolding or other surface on which the worker is standing, the brake system would gradually but quickly stop the drum from rotating, thus preventing additional cable from being paid out and breaking the fall of the worker. However, if the worker simply requires more cable to permit a greater range of motion within the work area, cable will be paid out as necessary. Conversely, as the worker approaches the safety device, the lifeline will be wound back onto the drum automatically due to the spring biased action of the drum.
A common problem with retractable lifeline safety devices of earlier forms is that the cable tends to act as a wick, drawing dirt and other contaminated materials into the inner assembly of the housing when the lifeline is rewound onto the drum. The dirt or other contaminants, such as asbestos, may foul the braking system, which may necessitate the disposal of the entire assembly, since many prior retractable lifeline safety devices are not easily repaired. This may happen with great frequency, since it is extremely important to inspect these assemblies for contamination frequently and dispose of them immediately when necessary, because of the nature of these devices as safety devices that are depended upon to save workers and others from serious injury or even death.
Prior art devices that illustrate these problems include that disclosed in U.S. Pat. No. 2,896,912 issued to Faugier et al. on Jul. 28, 1959. The safety apparatus disclosed therein shows a drum brake having two brake shoes, and a spiral spring, both the brake and the spring being exposed to the foreign matter potentially introduced into the system by the wicking action of the cable, as well as being exposed to moisture and other airborne contaminants that could lead to rust and corrosion. U.S. Pat. No. 2,990,131 issued to Carlsson on Jun. 27, 1961, although relying on a somewhat different braking system, suffers from the same drawbacks as the earlier reference.
The retractable lifeline safety device of the present invention overcomes the difficulties described above and affords other features and advantages heretofore not available.